Apparatus for automatic production and transportation of flaskless sand moulds in metal casting

ABSTRACT

In a machine for producing and conveying horizontally divided flaskless sand molds, two mold frame cavities are formed above and below a match plate having a pattern on both sides and being movable along horizontal guides relatively to the cavities which are defined by vertically moving mold frames and vertically moving press dies co-operating with said mold frames. The molding sand is introduced pneumatically into the cavities through apertures in the dies and thereafter pressed by a corresponding relative movement between said press dies and match plate, after which the match plate is separated from the mold halves by a corresponding relative movement between the press die and the mold frame on one hand, and the match plate on the other. The match plate is then moved laterally into a rest position and the mold is closed, if necessary, after the insertion of cores. The finished closed mold rests on the bottom press die which is substantially flush with the upper edge of the lower mold frame, and is then displaced laterally from the molding position by the match plate as it returns from its rest position. The ejected finished mold is added to a mold train, and the finished mold is at least supported on two sides by supporting means.

United States Patent 1191 Buhler APPARATUS FOR AUTOMATIC PRODUCTION AND TRANSPORTATION OF FLASKLESS SAND MOULDS IN METAL CASTING [76] lnventor: Eugen Buhler, Weg zur Walk 96,

Burtenbach, Kreis Gurizburg, Germany [22] Filed: Jan. 8, 1971 [21! Appl. No.: 105,067

Related US. Application Data [62] Division of Ser. No. 753,640, Aug. 9, 1968, Pat. No.

[56] References Cited UNITED STATES PATENTS 3,229,336 l/1966 Hunter et a1 164/200 X 3,008,199 ll/l96l Jeppesen 164/22 2,789,325 4/1957 McKee 164/202 2,908,951 10/1959 Melka 164/207 X 2,672,664 5/1954 Sudziarski 164/207 X 2,636,231 4/1953 Dougherty 164/22 3,293,703 12/1966 'Iaccone 164/160 Ronceray 153/212 1451 July 10, 1973 2,894,299 7/1959 Buhrer 164/239 3,273,207 9/1966 Taccone 164/40 X 3,540,516 11/1970 Taccone 164/29 X FOREIGN PATENTS OR APPLICATIONS 868,409 5/ 1961 Great Britain 164/ 160 Primary Examiner-J. Spencer Overholser Assistant Examiner-John E. Roethel Attorney-Holman & Stern [57] ABSTRACT ln a machine for producing and conveying horizontally divided flaskless sand molds, two mold frame cavities are formed above and below a match plate having a pattern on both sides and being movable along horizontal guides relatively to the cavities which are defined by vertically moving mold frames and vertically moving press dies co-operating with said mold frames. The molding sand is introduced pneumatically into the cavities through apertures in the dies and thereafter pressed by a corresponding relative movement between said press dies and match plate, after which the match plate is separated from the mold halves by a corresponding relative movement between the press die and the mold frame on one hand, and the match plate on the other. The match plate is then moved laterally into a rest position and the mold is closed, if necessary, after the insertion of cores. The finished closed mold rests on the bottom press die which is substantially flush with the upper edge of the lower mold frame, and is then displaced laterally from the molding position by the match plate as it returns from its rest position. The ejected finished mold is added to a mold train, and the finished mold is at least supported on two sides by supporting means.

33 Claims, 27 DrawingFigures United States Patent 91 m1 3,744,549

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PATENTEDJULIOIQTS SKEH 110F14 PATENTEBJUI. I 01915 SIiEEF 1300 14 APPARATUS FOR AUTOMATIC PRODUCTION AND TRANSPORTATION OF FLASKLESS SAND MOULDS IN METAL CASTING This application is a divisional application of copending application Ser. No. 753,640 filed Aug. 19, 1968, which will become US. Pat. No. 3,556,196 dated Jan. 19, 1971.

The invention relates to an apparatus for the automatic mechanical production as well as for the conveyance of horizontally divided flaskless sand molds.

In U.S. Pat. No. 1,021,938 is described a machine, operated rhythmically by a pressure medium, which has vertically moving mold frames defining together a frusto-pyrimidal and vertically movable press dies, both arranged above and below a horizontal match plate that can be swung in a horizontal plane.

This known mold making machine permits the semiautomatic production of flaskless horizontally divided casting molds, but it has the disadvantage that the molding sand must be manually placed in the mold frames and that the finished mold can only be conveyed on base plates. The lifting of the finishedmolds from the mold making machine, and the transport of the latter to the casting pit must be effected by hand. The great amount of manual work involved. in the known machine causes loss of time andhigh: wage costs and precludes the efficiency of automatic procedures. Furthermore, the supply of a great number of base plates requires considerable investment costs. US. patent;

3,229,366 describes a mold, making machine of the above mentioned. general. type, but with. a stationary upper mold frame, where themolding sand is pneumatically blasted through-lateral slots in.both moldframes into the interior thereof. Due to the known arrangement, the costly manual labor incharging the molding sand is avoided and the process, is accelerated. However, this machine has the disadvantage that the molding sand blasted into the interior of the mold frames mixes with the compressed air conveying it-andthe pattern halves are damaged by the resulting erosive action of the sand blower, and also difficulties are encountered in eliminating the entrained air.

Both of the known machines have the same disadvantage insofar as the finished molds must be transferred from the mold making machine to the casting pit by hand, and they require base plates for that purpose. Furthermore, the finished molds must be covered with so-called jackets before they can be moved away, in order to withstand the pressure of the liquid metal during casting. The placing of the jackets over the finished molds must also be accomplished by hand. Needless to say, these jackets involve a considerable investment.

Swiss Pat. No. 364,078 and US. Pat. No. 3,008,199 disclose a plant for the production of vertically divided flaskless sand molds, often called, stackmolds, because the opposing concave end-faces of the consecutive mold parts (forming a horizontally extending stack) define the mold cavities. Withthese machines the molding sand is introduced by blasting through a lateral slot of a stationary horizontal mold frame defining a cavity between two verticalmatch plate halves. The molding sand is subsequently pressed by moving one of the match plate halves. Thereafter, the other match plate half is swung away from the finished mold body and the latter is pushed by horizontal movement of the first match plate half onto a horizontal conveyor track where it joins as a newly added part a mold train stack moving toward a casting pit. This known machine has the advantage of being completely automatic, but because of the vertical division of the mold, there are difficulties regarding the insertion of the core and the production of larger castings, since the finished mold bodies cannot withstand high internal pressure. With this machine, the mold parts are laterally supported on both sides by stationary support bars. However, the friction between the support bars and the mold parts is so high that they contribute to damage of the mold parts rather than to reinforce them. Hence, the distance of transportation for the mold stack must be small between the molding machine and the casting pit.

US. Pat. No. 2,636,231 describes a machine for the automatic production of flaskless horizontally divided sand molds which has vertically moving mold frames defining together a frusto-pyramid and cooperating with horizontal match plate which can be swung horizontally froma rest position into a operative position. The upper mold frame has a perforated cover and the lower mold frame cooperates with a stationary perforated bottom plate. Horizontally movable sand chambers can be moved from loading positions underneath of respective sand hoppers into operating positions upward andbelow said mold frames. Air cylinders are arranged upward and below of such operating positions of such sand chambers and cooperate with the sand chambers so that when compressed air is introduced into said air cylinders, the molding sand is blasted through said perforations of said mold frames into the cavities of the latter. Despite its considerable complexity and bulkiness, this machine is only suitable for the production of small molds of little height. Furthermore, no provision is made for transportation of the finished molds.

German Pat. No. 871,499 discloses a machine for the automatic production of flaskless horizontally divided sand molds which have vertically movable closed mold frames defining a mold cavity with vertical side walls and cooperating with a match plate movable along horizontal guides between a rest position and an operative position and ejecting the finished molds when moving into the operative position. The mold sand is pneumatically blasted out of a retractable filling duct into the upper mold frame, after which the match plate with the mold frames is tilted around a horizontal axis and the sand is then blasted into the other mold frame. The tiltingmechanism makes the machine complex and costy.

All of the above described known machines and plants have the disadvantage that the change of patterns is cumbersome and time-consuming, and the known arrangements are therefore uneconomical in the production of smaller series of castings or in the production of single castings.

The object of the present invention is, on the one hand,to achieve a fully automatic operation in the pro duction of horizontally divided molds for small and larger castings thereby avoiding base plates and jackets, and on the other hand, to make such an automatic process economical by rapid pattern changes, not only for the production of large runs, but also for the production of small runs or single pieces as well as for small castings.

SUMMARY OF THE INVENTION The invention relates to a flaskless sand mold producing and conveying plant having a. a sand mold making machine comprising substantially vertically movable upper and lower mold frames, upper and lower perforated dies respectively contained in said mold frames and capable of relative movement thereto, a match plate having patterns on the top and bottom surfaces thereof mounted for movement along horizontal guides from a rest position laterally adjacent said sand mold making machine to an operative position between said mold frames and dies, and an extendab'le sand chamber arranged respectively above the upper mold frame and below the lower mold frame, each of said sand chambers being connected to a sand tank laterally arranged to said upper and lower mold frames, a filling device for said sand tank, and a pressure gas tank connectable by, control valve means to each of said chambers;

b. conveying means laterally adjacent said sand mold making machine opposite to the rest position of said match plate and being operatively connected with said match plate;

c. and supporting means bearing against at least two sides of a finished mold and following the movements of that mold in cooperation with said conveyor means;

the plant operating such that said match plate is clamped by said upper and lower mold frames to form mold cavities, the mold sand is pneumatically filled into said cavities, said upper and lower dies compress that sand against said patterns to form a mold, said mold frames and dies are vertically moved from said match plate, said match plate is laterally moved to said rest position, the so-formed mold is closed and when said match plate is returned to said operative position the finished mold is ejected onto said conveying means and said supporting means are placed on said mold to go with it to a place near the knock-out place from where it returns to its starting place.

The match plate of the mold making machine of such a plant is preferably designed as a hollow body, the cavity of which is defined by a perforated top plate and a perforated bottom plate and by a match plate frame and is connectable selectively to a vacuum source or to a pressure source. The top and bottom plates are preferably pivotally mounted on said match plate frame. The patterns carried by such a match plate have preferably the form of integer pattern units which, in the case of the top surface, include an inlet, a feeder, an ingate and the respective pattern half. A test plate may be provided, having identical apertures and dimensions to said top and bottom plates of the match plate facilitate pattern changes and arrangements.

The mold making machine of the plant according to the present invention has preferably a cross-slide frame containing at least one extra match plate so that white said match plate is in said rest position it may be exchanged with said extra match plate.

The horizontal match plate guides of the mold making machine of the plant according to the present invention have preferably the form of gas tight ducts which are selectively connectable to a vacuum and pressure source and said ducts communicate with said match plate cavity to evacuate or pressurize the same.

The conveyor means of the plant according to the present invention are preferably driven conveyor means and may have the form of an endless steel belt. The arrangement may be such that said steel belt is driven when a pre-determined pressure is exerted by the last ejected mold.

A hydraulic drive may be mounted below said conveyor means which acts by way of forked intermediate members on said match plate and by way of sliding forks on the supporting means of the second last ejected mold. The forked intermediate members may be attached to the match plate by a hook which allows relative lateral movements as well as raising said match plate relative to said hook.

Infra-red heaters are preferably arranged above and below said rest position of the match plate to heat the same.

The supporting means of the plant according to the present invention may either have the form of endless belts arranged laterally adjacent said conveyor means or they may have the form of two horizontally pivoted clamping plates which support the lateral side of the finished mold. in the latter case, the supporting means are lowered onto the finished mold after it is ejected from the mold making machine, and the clamping plates have each at least one counter weight for the opening and closing thereof. In a preferred embodiment, said counter weight actuates said clamping plates by means of levers, said counter weight being connected to a trolley which in turn runs on a track between the knock-out station and a station adjacent said mold making machine where said supporting means is lowered over said ejected finished mold, as it is lowered said clamping plates are in a spread position exceeding the width of said mold, and a weight plate connected by said levers to said clamping plates and said counter weight above the top of said mold actuates the closing of said spread clamping plates against said mold.

In one embodiment of the plant according to the present invention, the dies of the mold making machine are actuated by a hydraulic piston and cylinder, and the piston rod connecting said die to each respective piston pass through said respective upper and lower cham bers.

According to another embodiment of the plant of the present invention, said upper and lower sand chambers are respectively defined by annular pistons and cylinders having a cylindrical connecting tube actuating each respective die. The upper and lower mold frames of the mold making machine may be hydraulically actuated by pistons and cylinders mounted laterally said annular pistons and cylinders or they may be respectively hydraulically operated by concentric pistons and cylinders.

According to a preferred embodiment of the invention there may be two gas pressure lines and valves between said pressure gas tank and said upper and lower sand chambers, and the sand chambers and the mold sand tank may form a C in vertical cross-section, with said gas pressure line entering respectively at the upper and lower portions of the C.

The filling device of the plant according to the present invention preferably consists of a hopper opening into the top of the sand tank, and a hydraulically operated horizontal slide valve may be provided consisting of a carriage movable in a horizontal guide and a hori- BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a partial section of a schematic elevation of one embodiment of the mold making machine for sand mold production and conveyor plant according to the invention;

FIG. 2 to 6 show a simplified schematic lateral elevation, similar to FIG. 1, which represents the machine corresponding to its operation successively in pressing position, in lifting position, in core-inserting position, in mold-closing position and in mold ejecting position;

FIG. 7 shows a schematic elevation of the mold making machine as well as of the respective conveyor track for the finished mold train of the mold-production and conveyor plant during the ejection of a finished mold, turned by 90 about the vertical axis of the machine as compared to FIGS. 1 to 6;

FIG. 8 shows a schematic cross-section through the conveyor track for the mold train of the plant according to the invention with the supporting means according to the invention for supporting the side walls of the finished molds;

FIG. 9 shows a partial section of a schematic top view of a match plate, preferably to be used in combination with the plant according to the invention, a so-called top plate being inserted in the left half of the draw- FIG. 10 represents a section along the plane X-X in FIG. 9, seen in the direction of the arrows; which shows that in addition a so-called bottom plate is inserted in the left half of the match plate according to the invention;

FIG. 11 shows a side view in the direction of arrow XI in FIG. 9;

FIG. 12 shows a side view in the direction of arrow XII in FIG. 9;

FIG. 13 shows an enlarged schematic partial section along the plane X-X in FIG. 9, which represents the match plate illustrated in FIGS. 9 to 12 with the attached inlet, pattern, and a pattern unit according to the invention in the production of a mold half;

FIG. 14 shows a schematic side view in the direction of the arrow XIV in FIG. 9, in which the top and bottom part of the match plate is shown in a partly folded state;

FIG. 15 shows a schematic perspective view of a preferred embodiment of the match plate according to the invention used in combination with a mold making machine according to the invention.

FIG. 16 shows a schematic partial side view of an other embodiment of the sand mold production and conveyor plant according to the invention;

FIG. 17 shows a partial section of a top view of the plant represented'in FIG. 16;

FIG. 18 shows a partial section along the plane XVIII-XVIII in FIG. 17;

FIG. 19 shows a partial top view of the plant represented in FIG. 16 seen in the direction of the arrow XIX in FIG. 16;

FIG. 20 shows a schematic section along the plane XX-XX in FIG. 16, seen in the direction of the arrows;

FIG. 21 shows a schematic partial verticallongitudinal section through a modified embodiment of the mold frame and press die arrangement of a mold making machine according to the invention;

FIGS. 22 to 26 show respectively partial verticallongitudinal sections through the mold making machine of the sand mold production and conveyor plant represented in FIGS. 16 to 20 in various operating positrons,

and FIG. 27 is a view similar to FIG. 1 of another embodiment of the invention.

FIRST EMBODIMENT With reference to FIGS. 1 to 8 of the drawings we will now describe an embodiment of a sand mold production and conveyor plant according to the invention will now be described.

FIG. 1 shows a part ofthe mold making and conveyor plant according to the invention showing the foundation frame of the mold-making machine according to the invention with cross yoke A. In this foundation frame is held for vertical displacement a top die Ba, which is fixed, for example, in this embodiment of the invention during the working cycle of the machine. This top die can be set at different levels for the production of patterns of different profile height by means of a hydraulic drive Fa, so that the working strokes of the machine and their time intervals are kept as short as possible. An upper mold frame Ca is vertically displaceable with respect to top die Ba by means of a hydraulic drive Ea. A double-sided match plate D is at the beginning of the working cycle of the machine in the position represented in FIG. 1 of the drawings, in whichthe molding sand is introduced pneumatically into the machine. A bottom die Bb of the machine can be moved vertically up and down in known manner by means of a hydraulic drive Fb. A lower mold frame Cb is vertically displaceable relative to this bottom die Bb by means of a hydraulic drive Eb.

FIG. 7 of the drawings shows an ejection device G for a match plate D of the machine in a schematic representation. This device serves also to insert the match plate again into the machine and thus pushes the tinished mold at the same time onto a conveyor belt 1 of the plant according to the invention. The match plate D is either designed itself as a truck and is provided to this end with wheels, or it rests on a horizontally moving frame-shaped truck, whose inside width is greater than the bottom mold frame Cb. According to this embodiment of the machine the bottom mold frame together with the bottom die Bb can pass during the pressing operation through the frame-shaped truck lifting the match plate D upwards and pressing it against the top die Ba.

FIGS. 7 and 8 of the drawings also show the conveyor belt 1 of the mold-making plant according to the invention forming the conveyor track of the mold train, on which ejected finished molds are arranged. The edges of the horizontal separating joints of these flaskless sand molds have, according to the invention, complementary bevels L, which serve to fix the upper and lower mold halves during the feeding processes. They have been omitted for claritys sake in FIGS. 1 to 7, in the match plate.

FIG. 8 shows a schematic cross-section through the conveyor belt 1 and also supporting means according to the invention for the lateral support of the finished molds resting on the conveyor belt. These have, for example, the form of clamping plates M, as mentioned above, which are pressed by means of a controllable linkage, according to the invention, laterally against the finished molds so that the latter can withstand the casting pressure deformation force resulting from the feeding process. These clamping plates M can also be actuated, if this seems advisable, from the top, for example by using known weight irons as it is shown on the right of FIG. 8.

FIG. 1 of the drawings also shows the pneumatic filling device N for the molding sand of the mold-making plant according to the invention. The molding sand is accelerated during the filling process simultaneously with air from the top and from the side. In this way a uniform filling of both mold frames Ca and Cb is achieved. Louvered diaphragms ensure the proper air flow.

FIRST EMBODIMENT OPERATION The individual working cycles of the mold-making plant according to the invention will now be described on the basis of FIGS. 1 to 7 of the drawings.

FIG. I shows the first working stage. Here the upper mold frame Ca and the lower mold frame Cb are applied to the interposed match plate D. In this state the molding sand is introduced pneumatically by means of the device N. This is the basic first step for the pressing process.

FIG. 2 shows the position of the mold frames Ca and Cb after the pressing. In the compression of the molding sand, the bottom die Bb has moved upward relative to the lower mold frame Cb, which is held somewhat by a certain initial stress of the hydraulic drives Ea, Eb and has thus been protected from uncontrolled sliding down, for example, by its own weight. The bottom die Bb has lifted the match plate D from its rails and taken it upwards together with the upper mold frame Ca relative to the top die Ba, so that the molding sand contained in the upper mold frame has also been compressed. A slight backpressure can be exerted by means of the upper hydraulic drive Ea.

FIG. 3 of the drawing shows the detached position in which the two mold frames Ca and Cb are pulled apart by lowering the bottom die Bb and lower mold frame Cb without any relative movements with respect to the dies and mold frames. The match plate D is again placed on its frame-shaped truck or, if it is designed itself as a truck, on. the rails and is subsequently moved to the rear by means of the horizontally acting hydraulic drive indicated at G in FIG. 7 of the drawings. In case the match plate D is designed itself as a truck, a hook-shaped vertically detachable connection is provided between this hydraulic drive and the match plate D, likewise indicated in FIG. 7 (not numbered).

The removal of the match plate D results in the coreinserting position represented in FIG. 4. Cores can be inserted either by hand or by means of a special coreinserting mechanism. Subsequently the bottom die Bb with the lower mold frame Cb and the lower mold half moves up until it bears on the upper mold half, the two mold frames Ca and Ch being simultaneously pulled back or subsequently pulled back by'means of the hydraulic drives Ea and Eb so that they release the entire mold.

The mold is thus closed and rests in the position shown in FIG. on the bottom die Bb. In its following downward movement it is disengaged from the top die.

The bottom die subsequently moves so that it is aligned with the conveyor belt I. This position is the ejection position represented in FIG. 6.

If the match plate D and its frame-shaped truck are introduced again by means of a hydraulic drive G, the finished mold K is ejected at the same time onto the conveyor belt I as shown in FIG. 7.

The two mold frames Ca and Cb are subsequently raised and lowered again by means of their hydraulic drives Ea and Eb until they bear again on the match plate D, the starting position according to FIG. 1 has been reached again and the working cycle can start anew.

The finished molds form, as shown in FIG. 7, a closed mold train having two abutting surfaces each of the four lateral surfaces of the finished molds supporting one another. The contact pressure of the molds, which is equal to the ejection power and the driving force required for a non-driven conveyor belt must be limited so that overstress of the molds which might result in lateral destruction is avoided. To this end, the conveyor belt I can be driven-or supplemented, for example by means of a stepping mechanism, whose activity is preferably started by overpressure of the pressure medium actuating the hydraulic drive G.

The arrangement can be such that a synchronous motional impulse, slightly trailing behind the inserting movement of the match plate, is imparted to the conveyor belt, with the power of the inserting movement of the match plate being so limited that destruction of the finished molds is avoided. The driving power of the conveyor belt is preferably obtained from a power source producing power in excess of the introduction of the match plate.

The support of the exposed other two sides of the molds is effected, as mentioned above, by clamping plates. These run in synchronism with the conveyor belt I. They can be secured by a linkage on the belt or they can be articulated on weight irons guided at the top, or they can be secured on a'separate belt, which can follow, for example, by friction contact.

The control of the working cycle of the mold making plant according to the invention can be effected in a simple manner, for example, by limit switches over control pistons by means of a pressure medium. The thrusts of the various hydraulic drives, for example of the hydraulic drives Ba, Bb, Fa, Pb and G, can be limited by known means, for example, overflow valves.

The height and area of the molds can be increased by corresponding dimensioning of the parts of the plant, for example, of the mold frames, press-dies, conveyor belt etc. up to orders of magnitude which were possible so far only in automatic plants with mold flasks.

The double-sided support of the finished molds advancing on the conveyor belt I can be effected in a modification of the invention, instead of by the above described clamping plates, by conveyor belts arranged at both sides of the finished mold train and extending parallel to the conveyor belt I, whose bank surfaces are vertical. Such supporting conveyor belts can be either driven or non-driven. They can be covered, if necessary, with spur plates extending perpendicularly to the conveyor belt surfaces, which reach between the individual finished molds and support their end faces.

Both the conveyor belt I and the above mentioned supporting conveyor belts can be supported to such an 

1. A flaskless sand mold producing and conveying plant having a. a sand mold making machine comprising vertically moveable upper and lower mold frames, upper and lower dies respectively contained in said mold frames and capable of relative movement thereto, a hollow match plate having a series of apertures in its top and bottom surfaces for mounting patterns, said match plate having a top and bottom plate, said apertures extending to said top and bottom plates, said match plate being mounted for movement from a rest position laterally adjacent said sand mold making machine to a operative position between said mold frames and dies, and a pneumatic mold sand supply device ; b. conveying means laterally adjacent sAid sand mold making machine; c. and supporting means bearing against at least two sides of a finished mold, the plant operating such that said match plate is clamped by said upper and lower mold frames to form mold cavities, said pneumatic mold sand supply device fills said cavities, said upper and lower dies compress said sand against said patterns to form a mold, said mold frames and dies are vertically moved from said match plate, said match plate is laterally moved to said rest position, the so-formed mold is closed and when said match plate is returned to said operating position, the finished mold is ejected onto said conveying means and said supporting means are placed on said mold.
 2. A flaskless sand mold producing and conveying plant having a. a sand mold making machine comprising substantially vertically movable upper and lower mold frames, upper and lower perforated dies respectively contained in said mold frames and capable of relative movement thereto, a match plate having patterns on the top and bottom surfaces thereof mounted for movement along horizontal guides from a rest position laterally adjacent said sand mold making machine to an operative position between said mold frames and dies, and an extendable sand chamber being arranged respectively above the upper and below the lower mold frame, each of said sand chambers being connected to a sand tank laterally arranged to said upper and lower mold frames, a filling device for said sand tank, and a pressure gas tank connectable by control valve means to each of said sand chambers; b. conveying means laterally adjacent said sand mold making machine opposite to the rest position of said match plate and being operatively connected with said match plate; c. and supporting means bearing against at least two sides of a finished mold and following the movements of said mold in cooperation with said conveyor means: the plant operating such that said match plate is clamped by said upper and lower frames to form mold cavities, the mold sand is pneumatically filled into said cavities, said upper and lower dies compress said sand against said patterns to form a mold, said mold frames and dies are vertically moved from said match plate, said match plate is laterally moved to said rest position, the so-formed mold is closed and when said match plate is returned to said operative position the finished mold is ejected onto said conveying means and said supporting means are placed on said mold to go with it to a place near the knock-out place from where it returns to its starting place.
 3. The plant as claimed in claim 1, including a match plate frame and, the hollow of said match plate being connectable selectively to a vacuum source and a pressure source.
 4. The plant as claimed in claim 1, wherein said top and bottom plates are pivotally mounted on said match plate frame.
 5. The plant as claimed in claim 3, wherein integer pattern units are mounted on the outer surfaces of said top and bottom plates, and in the case of the top surface said pattern unit includes an inlet, a feeder, an ingate and the respective pattern half.
 6. The plant as claimed in claim 1, wherein test plates having identical apertures and dimensions to said top and bottom plates of the match plate are provided to facilitate pattern changes and arrangements.
 7. The plant as claimed in claim 2, wherein a cross-slide frame containing at least one extra match plate is provided adjacent said sand mold making machine so that while said sand match plate is in said rest position it may be exchanged with said extra match plate.
 8. The plant as claimed in claim 1, wherein said match plate is moved along guide means between said rest and operative positions, said conveying means being on the opposite side of said sand mold making machine when in said rest position, said guide means being gas tight ducts, selectively connectable to a vacuum and a pressure source and said ducts communicating with said match plate hollow To evacuate or pressurize the same.
 9. The plant as claimed in claim 2, wherein said conveyor means is a driven conveyor.
 10. The plant as claimed in claim 9, wherein said conveyor is an endless steel belt.
 11. The plant as claimed in claim 10, wherein said steel belt is driven when a pre-determined pressure is exerted by the last ejected mold.
 12. The plant as claimed in claim 1, wherein a hydraulic drive is mounted below said conveyor means which acts by way of forked intermediate members on said match plate and by way of sliding forks on said supporting means of the second last ejected mold.
 13. The plant as claimed in claim 12, wherein said forked intermediate member is attached to said match plate by a hook which allows relative lateral movement as well as raising said match plate relative to said hook.
 14. The plant as claimed in claim 12, wherein said hydraulic drive is connected to said forked intermediate members and said sliding forks such that when said forked intermediate members bring said match plate from said rest position to said operative position thereby ejecting said finished mold, a predetermined delay exists before said sliding forks are actuated to move the second last ejected mold.
 15. The plant as claimed in claim 14, wherein a spring buffer is arranged between said forked intermediate members and said sliding fork to cushion the thrust.
 16. The plant as claimed in claim 2, wherein infra-red heaters are arranged above and below said rest position of said match plate to heat the same.
 17. The plant as claimed in claim 2, wherein said supporting means are endless belts arranged laterally adjacent said conveyor means.
 18. The plant as claimed in claim 2, wherein said conveyor means is an endless conveyor belt and vertical guides are laterally adjacent said belt, said supporting means of said finished mold comprising two horizontally pivoted clamping plates, which plate support the lateral sides of said finished mold.
 19. The plant as claimed in claim 18, wherein said supporting means are lowered onto said finished mold after it is ejected from said mold making machine, and said clamping plates have at least one counter weight for the opening and the closing thereof.
 20. The plant as claimed in claim 19, wherein said counter weight actuates said clamping plates by means of levers, said counter weight is connected to a trolley which in turn runs on a track between a knock-out station and a station adjacent said mold making machine where said supporting means is lowered over said ejected finished mold, as it is lowered said clamping plates are in a spread position exceeding the width of said mold, and a weight plate connected by said levers to said clamping plates and said counter weight abuts the top of said mold and actuates the closing of said spread clamping plates against said mold.
 21. The plant as claimed in claim 18, wherein said supporting means for each finished mold has two pairs of said clamping plates for supporting all four sides.
 22. The plant as claimed in claim 20, wherein each said clamping plate has a vertical strip on the side remote from said mold making machine, said vertical strip has a wedgeshaped cross-section and is attached to said clamping plate to allow elastic lateral movement, the length of said clamping plate plus said vertical strip is substantially equal to the length of said finished mold in the direction of said conveying means.
 23. The plant as claimed in claim 20, wherein said track has a section at said knock-out station and said station adjacent said mold making machine which are lowered by means of hydraulic devices.
 24. The plant as claimed in claim 2, wherein said dies are actuated by a hydraulic piston and cylinder, and the piston rods connecting said die to each respective piston pass through said respective upper and lower sand chambers.
 25. The plant as claimed in claim 2, wherein said upper and lower sand chambers are respectively defined by annular pisTons and cylinders having a cylindrical connecting tube actuating each respective die.
 26. The plant as claimed in claim 2, wherein said die apertures are truncated cones in vertical cross-section.
 27. The plant as claimed in claim 2, wherein said die apertures are slots and elements in said slots are actuated like louvers.
 28. The plant as claimed in claim 1, wherein said pneumatic mold sand supply device comprises a gas compressor, a pressure gas tank, a mold sand tank laterally arranged to said upper and lower mold frame, a filling device for said sand tank, at least one gas pressure line and valve between said pressure gas tank and said sand mold tank to admit gas and force the sand into said respective mold cavities through upper and lower sand chambers, there being two gas pressure lines and valves between said pressure gas tank and said mold sand tank, said upper and lower sand chambers and the mold sand tank forming a C in vertical cross-section, and said two gas pressure lines respectively enter at the upper and lower portions of the C.
 29. The plant as claimed in claim 1, wherein said upper and lower dies have vents in their surfaces facing that mold cavities, which vents are in communication with die cavities, which in turn are selectively connected to vacuum and pressure sources.
 30. The plant as claimed in claim 2, wherein said upper and lower mold frames are respectively hydraulically actuated by pistons and cylinders mounted laterally said annular pistons and cylinders.
 31. The plant as claimed in claim 2, wherein said upper and lower mold frames are respectively hydraulically operated by concentric annular pistons and cylinders.
 32. The plant as claimed in claim 28, wherein said two gas pressure lines branch off from a single pressure gas feed connected with said pressure gas tank and containing one valve.
 33. The plant as claimed in claim 28, wherein said filling device consists of a hopper opening into the top of the sand tank, and a hydraulically operated horizontal slide valve consisting of a carriage movable in a horizontal guide and a horizontal cover plate fitted to said carriage by toggle levers to close the hopper entrance. 